Wireless communications rely on various protocols for transmitting communications between transmitters and receivers. Some protocols reflect the physical layer of communications.
When communications are transmitted on the physical layer, spreading sequences may be used to overcome noise that may exist on the signal. Specifically, each bit in the communication is encoded with a predefined series of bits. The number of bits in the series is specified by a spreading factor. For example, a zero (0) may be encoded with a first predefined series of bits having a length defined by the spreading factor. Conversely, a one (1) may be encoded with a second predefined series of bits having a length defined by the spreading factor.
A set of spreading sequences used in the IEEE 802.15.4k amendment transmission protocol is based on alternating patterns of 1's and 0's (i.e., alternating sequence). In other words, in the spreading sequence encoding, a 1 precedes and follows a 0. Conversely, a 0 precedes and follows a 1. For example, for a spreading factor of 8, a input bit value of 1 may produce output of 0101 0101 and an input bit value of 0 may be produce output of 1010 1010. Alternatively, for a spreading factor of 8, a input bit value of 1 may produce output of 1010 1010 and an input bit value of 0 may be produce output of 0101 0101.